ES8601798A1 - An improved polyvalent ion exchanged adsorbent for air separation. - Google Patents

An improved polyvalent ion exchanged adsorbent for air separation.

Info

Publication number
ES8601798A1
ES8601798A1 ES527240A ES527240A ES8601798A1 ES 8601798 A1 ES8601798 A1 ES 8601798A1 ES 527240 A ES527240 A ES 527240A ES 527240 A ES527240 A ES 527240A ES 8601798 A1 ES8601798 A1 ES 8601798A1
Authority
ES
Spain
Prior art keywords
polyvalent
faujasite
ion
ions
exchanged
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
ES527240A
Other languages
Spanish (es)
Other versions
ES527240A0 (en
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Air Products and Chemicals Inc
Original Assignee
Air Products and Chemicals Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Air Products and Chemicals Inc filed Critical Air Products and Chemicals Inc
Publication of ES8601798A1 publication Critical patent/ES8601798A1/en
Publication of ES527240A0 publication Critical patent/ES527240A0/en
Granted legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
    • B01J20/16—Alumino-silicates
    • B01J20/18—Synthetic zeolitic molecular sieves
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/02—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography
    • B01D53/04—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by adsorption, e.g. preparative gas chromatography with stationary adsorbents
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/02—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material
    • B01J20/10—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising inorganic material comprising silica or silicate
    • B01J20/16—Alumino-silicates
    • B01J20/18—Synthetic zeolitic molecular sieves
    • B01J20/186—Chemical treatments in view of modifying the properties of the sieve, e.g. increasing the stability or the activity, also decreasing the activity
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2253/00—Adsorbents used in seperation treatment of gases and vapours
    • B01D2253/10—Inorganic adsorbents
    • B01D2253/106—Silica or silicates
    • B01D2253/108—Zeolites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2256/00—Main component in the product gas stream after treatment
    • B01D2256/10—Nitrogen
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2256/00—Main component in the product gas stream after treatment
    • B01D2256/12—Oxygen
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/10—Single element gases other than halogens
    • B01D2257/102—Nitrogen
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D2257/00—Components to be removed
    • B01D2257/80—Water

Landscapes

  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Inorganic Chemistry (AREA)
  • Organic Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Solid-Sorbent Or Filter-Aiding Compositions (AREA)
  • Silicates, Zeolites, And Molecular Sieves (AREA)
  • Separation Of Gases By Adsorption (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)
  • Oxygen, Ozone, And Oxides In General (AREA)
  • Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)

Abstract

A compsn. contg. at least 50 wt.% faujasite is (I) ion exchanged with polyvalent ions e.g. Mg, Ca, Sr, Ba or esp. Ca or their mixts. and (II) then thermally activated to remove a substantial portion of the zeolitic H2O such that the polyvalent ions are in a dehydrated or dehydroxylated state. The adsorbent prod. contains at least 50 wt.% faujasite with the majority of its ion exchange capacity in a polyvalent form. Pref. (I) is effected in aq. medium and in (II) the compsn. contains upto 30 wt.% H2O and is subjected to a pressure of 0.1-10 atmos., in a flow of inert purge gas passed at a rate of 0.006-6 l/min. for a time of less than 2.5 mins. and then heated to a temp. in the range 300-650 deg. C at a rate of 0.1-40 deg. C/min. and maintained at this temp. for at least 12 hrs. Pref. the starting compsn. is a 13X-type zeolite contg. faujasite with a Si/Al ratio of from 1-2. - Prods. esp. those contg. Ca ions have superior utility for sepg. air into N2 and O2 and for the adsorption of N2 from gas mixts. (0/4) EPAB- EP-109063 B A method for preparing a polyvalent-ion-exchanged alumino-silicate zeolite coprising at least 50% by weight faujasite and the faujasite portion thereof having more than 50% of its exchangable ions exchanged into the polyvalent form which method comprises ion exchanging the faujasite-containing zeolite with polyvalent ions and thermally activating the polyvalent ion exchanged zeolite, characterised in that the activating step comprises: (a) subjecting the ion-exchanged zeolite to - pressures in the range of 0.1 bar to 10.13 bar (0.1 to 10.0 atmospheres) while maintaining a flow of a nonreactive purge gas at a molar mass velocity of 0.5 to 100 Kg mole/m2/h and a residence time of no greater than 2.5 min., followed by (b) heating the material at a temperature ramp of 0.1 to 40 deg. C/min. up to temperatures of above at least 300 deg. C and no greater than 650 deg. C and maintaining the material at these temperatures for a period of at least 12 hours. - (28pp) USAB- US4481018 A A polyvalent ion exchanged absorbent compsn. comprises at least 50% faujasite having most of its ion exchange capacity in the polyvalent form. It is prepd. by initially ion exchanging the material with polyvalent ions. The material is then thermally activated to remove most of the zeolitic water and give a preponderance of the polyvalent ions in a dehydrated/dehydrocyclated state. During this step, the water vapour pressure is maintained at 0.1-10.0 atmospheres and a flow of non-reactive purging gas is maintained. The - material is maintained at 300-650 deg.C until the desired level of selectivity for a desorbing nitrogen is obtd..
ES527240A 1982-11-15 1983-11-14 A METHOD OF PREPARING A CRYSTALLINE ALUMINOSILICATE ZEOLITE Granted ES527240A0 (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US06/441,822 US4481018A (en) 1982-11-15 1982-11-15 Polyvalent ion exchanged adsorbent for air separation

Publications (2)

Publication Number Publication Date
ES8601798A1 true ES8601798A1 (en) 1985-11-16
ES527240A0 ES527240A0 (en) 1985-11-16

Family

ID=23754432

Family Applications (2)

Application Number Title Priority Date Filing Date
ES527240A Granted ES527240A0 (en) 1982-11-15 1983-11-14 A METHOD OF PREPARING A CRYSTALLINE ALUMINOSILICATE ZEOLITE
ES532926A Granted ES532926A0 (en) 1982-11-15 1984-05-30 A PROCEDURE FOR THE SEPARATION, AT LEAST PARTIAL, OF A BINARY MIXTURE OF NITROGEN AND OXYGEN.

Family Applications After (1)

Application Number Title Priority Date Filing Date
ES532926A Granted ES532926A0 (en) 1982-11-15 1984-05-30 A PROCEDURE FOR THE SEPARATION, AT LEAST PARTIAL, OF A BINARY MIXTURE OF NITROGEN AND OXYGEN.

Country Status (10)

Country Link
US (1) US4481018A (en)
EP (1) EP0109063B1 (en)
JP (1) JPS59107920A (en)
KR (1) KR880000126B1 (en)
AT (1) ATE42913T1 (en)
CA (1) CA1214450A (en)
DE (1) DE3379834D1 (en)
ES (2) ES527240A0 (en)
MX (1) MX159350A (en)
ZA (1) ZA838476B (en)

Families Citing this family (57)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4544378A (en) * 1982-11-15 1985-10-01 Air Products And Chemicals, Inc. Nitrogen adsorption process
JPS60179134A (en) * 1984-02-28 1985-09-13 Union Showa Kk Molecular sieve molded body
US4557736A (en) * 1984-10-29 1985-12-10 Air Products And Chemicals, Inc. Binary ion exchanged type X zeolite adsorbent
EP0196103A3 (en) * 1985-03-28 1988-07-13 Air Products And Chemicals, Inc. Maximum aluminum x-type zeolite adsorbents
US4747854A (en) * 1986-05-22 1988-05-31 Air Products And Chemicals, Inc. Selective chromatographic process using an ion-exchanged, dehydrated chabazite adsorbent
US4744805A (en) * 1986-05-22 1988-05-17 Air Products And Chemicals, Inc. Selective adsorption process using an oxidized ion-exchanged dehydrated chabizite adsorbent
US4859217A (en) * 1987-06-30 1989-08-22 Uop Process for separating nitrogen from mixtures thereof with less polar substances
US4775396A (en) * 1987-11-05 1988-10-04 Union Carbide Corporation Selective adsorption of CO2 on zeolites
US4943304A (en) * 1989-04-06 1990-07-24 Air Products And Chemicals, Inc. Process for the purification of bulk gases using chabazite adsorbents
US5174979A (en) * 1989-10-06 1992-12-29 Uop Mixed ion-exchanged zeolites and processes for the use thereof in gas separations
US5013334A (en) * 1990-01-09 1991-05-07 Uop Methane purification by pressure swing adsorption
CA2041874C (en) * 1990-01-09 1999-04-06 Richard T. Maurer Separation of ethane from methane by pressure swing adsorption
FR2669242B1 (en) * 1990-11-16 1994-09-02 Ceca Sa INDUSTRIAL ADSORBENTS BASED ON ZEOLITES X WITH LOW SILICA CONTENT FOR THE NON-CRYOGENIC SEPARATION OF AIR GASES AND THEIR PREPARATION PROCESS.
US5203887A (en) * 1991-12-11 1993-04-20 Praxair Technology, Inc. Adsorbent beds for pressure swing adsorption operations
US5152813A (en) * 1991-12-20 1992-10-06 Air Products And Chemicals, Inc. Nitrogen adsorption with a Ca and/or Sr exchanged lithium X-zeolite
US5266102A (en) * 1992-09-23 1993-11-30 Air Products And Chemicals, Inc. O2 VSA process with low O2 capacity adsorbents
US5258060A (en) * 1992-09-23 1993-11-02 Air Products And Chemicals, Inc. Adsorptive separation using diluted adsorptive phase
US5258058A (en) * 1992-10-05 1993-11-02 Air Products And Chemicals, Inc. Nitrogen adsorption with a divalent cation exchanged lithium X-zeolite
US5354360A (en) * 1993-01-11 1994-10-11 Air Products And Chemicals, Inc. Magnesium A-zeolite for nitrogen adsorption
US5441557A (en) * 1993-12-14 1995-08-15 Praxair Technology, Inc. Enhanced gas separations and zeolite compositions therefor
US5454857A (en) * 1994-03-18 1995-10-03 Uop Air separation process
US5698013A (en) * 1994-03-18 1997-12-16 Uop Nitrogen-selective zeolitic adsorbent for use in air separation process
DE19518407A1 (en) * 1995-05-19 1996-11-21 Bayer Ag Process for the adsorptive oxygen enrichment of air with mixtures of molecular sieve zeolites
US5674311A (en) * 1995-10-20 1997-10-07 Praxair Technology, Inc. Adsorption process and system using multilayer adsorbent beds
FR2743507B1 (en) * 1996-01-16 1998-03-06 Air Liquide PROCESS FOR THE SEPARATION OF MIXTURES OF OXYGEN AND NITROGEN USING AN ADSORBENT WITH IMPROVED POROSITY
US5868818A (en) * 1996-08-08 1999-02-09 Tosoh Corporation Adsorbent for air separation, production method thereof, and air-separation method using it
EP0826631B1 (en) * 1996-08-30 2001-12-05 Tosoh Corporation Heat-resistant low-silica zeolite, and process for production and application thereof
FR2766476B1 (en) * 1997-07-22 1999-09-03 Ceca Sa IMPROVED ZEOLITIC ADSORBENT FOR THE SEPARATION OF AIR GASES AND PROCESS FOR OBTAINING SAME
FR2771656B1 (en) * 1997-12-01 2000-01-07 Air Liquide PSA PROCESS USING AN ADSORBENT WITH HETEROGENEOUS CAPACITY AND / OR SELECTIVITY PROPERTIES
US6171370B1 (en) 1998-03-04 2001-01-09 Tosoh Corporation Adsorbent for separating gases
US6780806B1 (en) 1998-12-30 2004-08-24 The Regents Of The University Of Michigan Lithium-based zeolites containing silver and copper and use thereof for selective absorption
FR2792220B1 (en) * 1999-04-19 2001-06-15 Air Liquide PSA PROCESS USING AN INTRINSICALLY RESISTANT ADSORBENT PROMOTING ADSORPTION KINETICS
US6340382B1 (en) 1999-08-13 2002-01-22 Mohamed Safdar Allie Baksh Pressure swing adsorption process for the production of hydrogen
US6451723B1 (en) 2000-07-07 2002-09-17 Honeywell International Inc. Polymer-bound nitrogen adsorbent and method of making and using it
ES2729331T3 (en) 2001-01-05 2019-10-31 Air Prod & Chem Manufacturing method for adsorbent laminates for high frequency PSA processes
CA2493605A1 (en) * 2001-07-25 2003-02-06 Richard A. Haase Processes and apparatus for the manufacture of polynuclear aluminum compounds and disinfectants, and polynuclear aluminum compounds and disinfectants from such processes and apparatus
GB2386889B (en) 2002-03-25 2006-01-11 Council Scient Ind Res Process for the preparation of molecular sieve adsorbent for selective adsorption of nitrogen and argon
PL372916A1 (en) 2002-04-11 2005-08-08 Richard A. Haase Water combustion technology-methods, processes, systems and apparatus for the combustion of hydrogen and oxygen
JP4025228B2 (en) * 2003-03-28 2007-12-19 カウンスィル オブ サイエンティフィック アンド インダストリアル リサーチ Preparation method of molecular sieve adsorbent for selective separation of air size / morphology
US20040267071A1 (en) * 2003-06-30 2004-12-30 Chevron U.S.A. Inc. Process for the oligomerization of olefins in Fischer-Tropsch derived feeds
US7319082B2 (en) * 2003-10-27 2008-01-15 Council Of Scientific And Industrial Research Process for the preparation of molecular sieve adsorbent for selective adsorption of oxygen from air
US7128776B2 (en) * 2004-03-10 2006-10-31 Air Products And Chemicals, Inc. Periodic high temperature regeneration of thermal swing adsorption systems
US7390294B2 (en) * 2004-05-28 2008-06-24 Ethicon Endo-Surgery, Inc. Piezo electrically driven bellows infuser for hydraulically controlling an adjustable gastric band
US7374565B2 (en) * 2004-05-28 2008-05-20 Ethicon Endo-Surgery, Inc. Bi-directional infuser pump with volume braking for hydraulically controlling an adjustable gastric band
US7351240B2 (en) * 2004-05-28 2008-04-01 Ethicon Endo—Srugery, Inc. Thermodynamically driven reversible infuser pump for use as a remotely controlled gastric band
US7481763B2 (en) * 2004-05-28 2009-01-27 Ethicon Endo-Surgery, Inc. Metal bellows position feedback for hydraulic control of an adjustable gastric band
US20050288740A1 (en) * 2004-06-24 2005-12-29 Ethicon Endo-Surgery, Inc. Low frequency transcutaneous telemetry to implanted medical device
US20050288739A1 (en) * 2004-06-24 2005-12-29 Ethicon, Inc. Medical implant having closed loop transcutaneous energy transfer (TET) power transfer regulation circuitry
US7191007B2 (en) * 2004-06-24 2007-03-13 Ethicon Endo-Surgery, Inc Spatially decoupled twin secondary coils for optimizing transcutaneous energy transfer (TET) power transfer characteristics
US7599744B2 (en) * 2004-06-24 2009-10-06 Ethicon Endo-Surgery, Inc. Transcutaneous energy transfer primary coil with a high aspect ferrite core
US7599743B2 (en) * 2004-06-24 2009-10-06 Ethicon Endo-Surgery, Inc. Low frequency transcutaneous energy transfer to implanted medical device
WO2006073824A2 (en) * 2004-12-30 2006-07-13 E.I. Dupont De Nemours And Company Methods of conditioning getter materials
US7404846B2 (en) * 2005-04-26 2008-07-29 Air Products And Chemicals, Inc. Adsorbents for rapid cycle pressure swing adsorption processes
US8173995B2 (en) 2005-12-23 2012-05-08 E. I. Du Pont De Nemours And Company Electronic device including an organic active layer and process for forming the electronic device
US8268269B2 (en) 2006-01-24 2012-09-18 Clearvalue Technologies, Inc. Manufacture of water chemistries
US20200063056A1 (en) * 2018-08-23 2020-02-27 M Chemical Company Adsorbent and process for methanol and oxygenates separation
CN110743492A (en) * 2019-10-18 2020-02-04 苏州立昂新材料有限公司 Lithium type low silicon faujasite mixed with multivalent cations, method for preparing same and use thereof

Family Cites Families (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE110478C (en) *
US2882244A (en) * 1953-12-24 1959-04-14 Union Carbide Corp Molecular sieve adsorbents
NL255368A (en) * 1959-09-25
US3140933A (en) * 1960-12-02 1964-07-14 Union Carbide Corp Separation of an oxygen-nitrogen mixture
US3140932A (en) * 1960-12-02 1964-07-14 Union Carbide Corp Separation of an oxygen-nitrogen mixture
NL274214A (en) * 1961-02-01
US3313091A (en) * 1963-11-04 1967-04-11 Exxon Research Engineering Co Vacuum cycle adsorption
US4056370A (en) * 1973-06-07 1977-11-01 Bayer Aktiengesellschaft Zeolite A with improved properties
JPS5829319B2 (en) * 1974-09-12 1983-06-22 第一工業製薬株式会社 cholesterol
CH623748A5 (en) * 1975-12-15 1981-06-30 Sergei Zinovievich Vasiliev Process for purifying gas mixtures
US4322394A (en) * 1977-10-31 1982-03-30 Battelle Memorial Institute Adsorbent regeneration and gas separation utilizing microwave heating
JPS56168833A (en) * 1980-06-02 1981-12-25 Mitsubishi Heavy Ind Ltd Oxygen absorbent from two-component gas of oxygen and nitrogen and its using method

Also Published As

Publication number Publication date
DE3379834D1 (en) 1989-06-15
EP0109063B1 (en) 1989-05-10
ATE42913T1 (en) 1989-05-15
JPS59107920A (en) 1984-06-22
ES8603762A1 (en) 1986-01-01
KR880000126B1 (en) 1988-03-12
ZA838476B (en) 1985-07-31
US4481018A (en) 1984-11-06
KR840006618A (en) 1984-12-01
EP0109063A2 (en) 1984-05-23
ES532926A0 (en) 1986-01-01
CA1214450A (en) 1986-11-25
MX159350A (en) 1989-05-17
ES527240A0 (en) 1985-11-16
EP0109063A3 (en) 1985-06-12

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Legal Events

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FD1A Patent lapsed

Effective date: 19971001